(n.) Used to describe someone who is an illiterate douche. Coupled with a case of arrogance, ignorance, and lacking confidence. People possessing the title of dickhead can easily be found at forums, message boards, and more specifically, at Reddit and Urban Dictionary. People often developed personalities that displeases others, which the witnesses often called that person a dickhead. Used figuratively most often.

a person who thinks they are right all of the time despite actual correct facts which can contradict their beliefs they stand proud and believe/yell that they are right, they try to be the bigger man to smaller/skinnier kids/people; they tend to try and make fun of people who won't "fight back"

Oh man he was such a Dickhead to me I told him that the way you do the problem is this way and he said to me...NO IT'S THIS WAY! YOU FAGGOT! shut up!

A complete idiot who is stupid and despised by everybody. Their kind are discriminated due to their unacceptable behaviours. Ones that you would love to hit when you see them.

Timothy is such a dickhead, although he doesn't have a dick.
Timothy is such a pervert, he is always trying to touch girls, he is such a dickhead.
Timothy always do nothing and pretends he has done everything, he is such a dickhead.
Timothy always think he is the director of the company although he is just an insignificant little idiot, he is such a dickhead.